Getting my 3.5 Metal Cat fitted and tuned next week.

Does anyone know if this will increase the exhaust noise or change the note?

not really mate... the only noticeable increase in sound is from better flow... sounds like the kitchen sink tap when you press on the loud peddle

Yes

Yeah definitely.

I got a bigger dump as well and I can hear the turbo much more easily now. Love that whistle....

Yeah definitely. 

I got a bigger dump as well and I can hear the turbo much more easily now.  Love that whistle....

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Yep. Gotta agree with the chain-smoking kid

my 3.5 cat didnt change much noise wise at all... probly 2% louder lol

ive got 4 inch cat and dump and it sounds awsome ya can really hear the air whilstling through it all.

I reckon its made a big differance to the note.

I got a 40rwkw gain

I ended up getting a custom made exhaust instead of replacing just the cat.

SS 3.5 dump to 3.5 metal cat splits to twin 2.5 inch into 2 mufflers and twin 2.5 outlets

Sounds AWESOME!